Field of the Invention
The present invention relates to a substrate processing device and a substrate processing method for supplying a processing liquid to a substrate to carry out a chemical treatment such as etching while rotating the substrate. The substrate to be processed includes substrates, for example, a semiconductor wafer, a substrate for an optical disk, a substrate for a magnetic disk, a substrate for a magneto-optical disk, a substrate for a photomask, a substrate for a solar cell, and the like.
Description of the Background Art
Although a series of processing steps for a substrate such as a semiconductor wafer have a plurality of film forming steps for forming a thin film of a metal, a photoresist or the like on a front surface (“an upper surface”) of the substrate, a film is also formed on a back surface (“a lower surface”) of the substrate or a peripheral edge part of the upper surface of the substrate at the film forming step in some cases. In general, however, the film formation is required for only a circuit formation region in a central part of the upper surface of the substrate in the substrate. In cases where the film is formed on the back surface of the substrate or the peripheral edge part of the upper surface of the substrate, a thin film formed on the peripheral edge part of the upper surface of the substrate may be peeled by contact with another device at a subsequent step to the film forming step, and may cause reduction in yield or a trouble of a substrate processing device itself.
Therefore, there is proposed a substrate processing device for carrying out so-called bevel etching, that is, previously supplying a processing liquid having its temperature controlled to a peripheral edge part of a substrate held in a substantially horizontal condition while rotating the substrate, thereby removing a thin film formed on the peripheral edge part of a upper surface of the substrate.
For example, the substrate processing device described in Japanese Patent Application Laid-Open No. 2004-6672 serves to supply the etchant from the nozzle taking an opposed shape to the central part in the lower surface of the substrate held in a substantially horizontal condition to the lower surface of the substrate while rotating the substrate, and to cause the etchant spreading toward the peripheral edge part by the action of centrifugal force to go around the peripheral edge part of the upper surface of the substrate, thereby etching the peripheral edge part of the upper surface of the substrate.
Moreover, the substrate processing device described in Japanese Patent Application Laid-Open No. 2008-47629 has the blocking member which is opposed to the upper surface of the substrate above the substrate and serves to supply the processing liquid from the nozzle disposed on the peripheral edge part of the blocking member toward the peripheral edge part of the upper surface of the substrate while rotating the substrate in the substantially horizontal plane, thereby etching the peripheral edge part of the upper surface of the substrate.
However, the devices disclosed in Japanese Patent Application Laid-Open Nos. 2004-6672 and 2008-47629 have a problem in that the amount of the processing liquid and the processing time which are required for the etching in the peripheral edge part are increased because the temperature of the peripheral edge part is reduced due to the rotation of the substrate, resulting in decrease in the etching rate.
In the technique of this type, it is demanded to reduce an etching width in the peripheral edge part (“end”) of the upper surface of the substrate as small and evenly as possible in order to effectively utilize, as a device, an area over the substrate which is as large as possible. In the technical field of manufacture of a semiconductor device, particularly, it is desired to decrease an etching width of 2 to 3 mm in the related art down to 1 mm or less in order to reduce a loss in a peripheral edge part of a wafer which is increased with increase in diameter of a semiconductor wafer, for example.
As a method for reducing the etching width by the substrate processing device described in the Japanese Patent Application Laid-Open No. 2004-6672, it is supposed to decrease an amount of supply of the processing liquid and to increase the rotating speed of the substrate in order to reduce an amount of wraparound of the processing liquid toward the upper surface of the substrate. According to the method, although an average etching width can be reduced, uniformity of the etching width is deteriorated, for example, the amount of wraparound of the processing liquid to the peripheral edge part is controlled with difficulty so that a portion to be etched locally and greatly appears. Furthermore, there is also a problem in that the temperatures of the peripheral edge part and the processing liquid in the peripheral edge part are lowered, resulting in reduction in an etching rate.
In order to decrease the etching width by the substrate processing device described in the Japanese Patent Application Laid-Open No. 2008-47629, it is necessary to decrease the amount of supply of the processing liquid to be supplied to the peripheral edge part of the substrate. However, there is a problem in that the etching rate in the peripheral edge part of the substrate is reduced due to decrease in the amount of the processing liquid and reduction in the temperature of the processing liquid in a pipe due to the decrease.
These are problems which are not limited to the etching using an etchant, but are caused in general processing for carrying out a chemical treatment for a substrate by using a processing liquid having a chemical activity (chemical reactivity) varied depending on a temperature (a processing liquid having a reaction rate increased with a rise in temperature).